| In the western region of Henan, there have become major constraint factors for local sustainable development of agriculture, because of seasonal drought, serious soil erosion and degradation of soil quality. Due to seasonal drought obviously, serious uneven temporal and spatial distribution of precipitation, larger dry area with serious drought, it is difficult for more than 40% of the dry farmland to achieve two crops a year, and the light and heat resources should not been made sufficient used.As China's major agricultural region, with the general trend of global climate change having a great impact on agriculture, the characteristics of agricultural resources in the region should be considered so that the potential water-saving of regional plant system can be fully dug out. There has been a significant and positive far-reaching significance for promoting the region sustainable development of agriculture in the future to explore the planting structure and mode which are suited for making practical and efficient use of water resources, maximize water use rate and water use efficiency, set up and optimize water-saving and efficient plant systems, improve crop water requirements in line with the precipitation and rainfall use efficiency overall ,resolve the crisis of agricultural water resources in the region.From the perspective of resources, this study discussed in-depth the laws of climate change in the area; from a methodological point of view, the DSSAT crop growth model is introduced into the research, and its simulation validation and sensitivity has been tested; from a combination of theory and practice point of view, the potential production of major crops, such as winter wheat , summer maize, summer peanut, summer soybeans, have been estimated, the crop cultivation schemes are optimized in order to optimize and screen out the best plant model.In this study, the major progress made and conclusions are as follows:(1) In Luoyang Mengjin, annual temperature became warming trend, according with the current global warming which is in the phase of continued warming-up. At present, the region is in the relatively warm period. During 1961-2007, the overall performance of the distribution of annual precipitation was in the relatively abundant periods before 1984, and followed by relatively less rainfall periods. In recent years, especially after 2004, annual precipitation showed a clear downward trend. There will be mainly dominated by relatively less precipitation in recent 8-12 years. The frequency of fluctuations of annual solar radiation and its phase changes were markedly increased during 1961-2007. Considering 1976 and 1985 as the cut-off points for the fluctuations, it can be divided into three stages. In recent years, solar radiation has being in the relatively low period. Through discussing the change trends of a long sequence of temperature, precipitation and solar radiation, and the inherent multi-scale law, it can provide valuable information for the local agricultural production.(2) The DSSAT crop growth model was verified and its sensitivity was tested, based on a database containing meteorological data, soil data, field management and experimental data and crop varieties data debugging and setting up. It was thought that the model focused more on comprehensive effects of the light, temperature, water, soil, as well as the development mechanism of crop growth, and highlighted more the response mechanism between crops, as the main bodies of the productive potential, and their impact factors. So that it can simulate well the final results of different crop management practices, and be able to simulate and evaluate the crop production potential, cultivation schemes, plant model optimized and screened, with high sensitivity. Therefore, the research results more objectively and effectively reveals the factors limited the growth and development of crops and limited extent, objectively and scientifically evaluated the potential and prospect of dry farming. So, it is a great important theoretical and practical significance to guide production practice and make the development countermeasures. (3) DSSAT model was applied to simulate and estimate the potential production of the main crops containing winter wheat, summer maize, summer soybeans and summer peanut in Luoyang Mengjin. The photo-temperature productivity can be used as the upper limit reference value of the average maximum yield in the irrigated areas, and the crops yield in the rain-fed areas can be referred by photo-temperate-precipitation productivity. During 1961-2007, the photo-temperature productivities of winter wheat and summer maize, summer soybeans and summer peanut were 9209.22 kg·hm-2,12039.96 kg·hm-2,3311kg·hm-2,3923kg·hm-2; photo-temperate-precipitation productivity of them were 5509.56 kg·hm-2,8894.42 kg·hm-2,2262.45kg·hm-2,2820kg·hm-2.(4) In order to harvest high yield of winter wheat, the best sowing date was before October 5. According to soil fertility, the suitable density of plants should be made sure, better at 250 plant? m-2 around. For summer maize, later seeding can reap higher yield than early seeding, better sowing dates from June 5 to 15th, suitable density help improve maize yield, better at 6-8 plant·m-2. Early seeding for summer soybean is advised, the best sowing date at June 5 around, the appropriate density is at 50-60 plant ? m-2. Summer peanut should be planted early, the best sowing date is at June 5. There is not clearly yield effect with density increasing, and the general density is 40-60 plant ? m-2.(5) In this study, considering the resource use efficiency of light, temperature, water, and economic benefits, 28 planting mode of 6 planting systems in Luoyang Mengjin were quantitative simulated and integrated assessment. The results showed that the optimum planting systems were 4 crops 2 years (the best cropping pattern was winter wheat-summer maize→winter wheat-summer peanut) and 2 crops 1 year (the best cropping pattern was winter wheat-summer maize). 3 crops 2 years (the best cropping pattern was winter wheat-summer maize→winter fallow-summer maize) can be proper developed, according to the actual situation in Luoyang Mengjin. The results of simulation and evaluation agree completely with the local circumstances. |
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